Method and mechanism for folding carton flaps



May 4, 1954 P. EL FISCHER TAL METHQD AND MEcHANIm FOR FoLnIaG CARTON FLAPs Filed nec. 2s, 195o f5 Sheets-Sheet 1 PAUL E. FlscHER NEAL l. PAULSEN May 4, 1954 P. E. FISCHER E1A'Al. 2,677,220

METHOD AND MECHANISM FOR FOLDING ARTON FLAPS S'Sheets-Sheet 2 Filed Dec. 25, 1950 PAUL E. FISCHER NEAL l. PAULSEN BVMW M mm /IV VENTORS- May 4, 15954 P. E. FISCHER ETAL 2,677,220

METHOD AND MECHANISM F OR FOLDING CARTON FLAPS Filed Dec. 23, 1950 5 Sheets-Sheet 3 /NVE/V7'0RS.'

PAUL E. FISCHER NEAL l. PAuLsEN May 4, 1954 .-P. 1E. P ,lscHR ETAL METHOD AND MECHANISM FOR FOLDING CARTON FLAPS Filed Dec. 23, 1950 May 4, 1954 P. 'Ea FISCHER ETAL 2,677,220

METHOD AND MECHANISM FOR FOLDING CARTON FLAPS Filed Dec. 23, 1950 5 Sheets-Sheet 5 PAUL E. FISCHER NEAL I. PAULSEN Patented May 4, 1954 UNITED STATES PATENT OFFICE METHOD AND MECHANISM FOR FOLDING CARTON FLAPS- Application December 23, 1950, Serial No. 202,518

9 Claims. l

This invention relates to improvements in methods and packaging machinery for folding closure flaps over the top of a closed and sealed carton and for applying heat to the flaps.

More specifically, the invention relates to improvements in steps of the closure of a carton. The type of carton, to which the method and apparatus are best adapted. is formed of a plurality of layers and has the side walls extending above the top of the carton to form top closure panels. In the first steps of closing the carton before operation by the present machine, the front and rear opposing top closure panels were brought into overlapping relationship over the carton top, and the adjoining connected side top-closure panels folded into triangularly shaped flaps or ears of double thickness extending outwardly in the plane of the carton top. Heat was applied to soften the thermoplastic adhesive which coated the carton material and the overlapping closure panels pressed together to cause them to adhere to form a seam. The doubled triangular side flaps also received heat and were laminated. Subsequently, a cooling medium was applied to solidify the adhesive and seal the carton. Thus an impervious air-tight seal was formed in the first stages of closing the carton. The problem then exists to accomplish the folding and sealing of the side flaps over the top of the carton to overlie the sealed closure panels without loosening or injuring in any way the impervious closure seal which has been formed.

When the flaps are folded over the top of the carton, the flaps are stressed at the fold lines, as the separate layers attached to both the side walls and underlying sealed panels have a tendency to slip or shift with respect to each other. The laminating adhesive is also under stress and some injury occurs to the solidified adhesive. These stresses cause the iiaps to have a tendency to spring up to unfolded position, tend to cause an unstable seal, and generally create an undesirable effect.

An object of the present invention is to provide a method and a device which will relieve the internal stresses and strains, present in folded, multiple layer carton closure flaps laminated with thermoplastic material, which cause the closure flaps to spring open and form an unstable fold.

A further object of the invention is to provide an improved mechanism which will, by the addition of heat, soften the thermoplastic adhesive between the laminated layers of carton flaps lll which have been folded over a carton top to allow the stressed layers to shift with respect to each other without permitting the heat to loosen the seal previously formed between the overlapping closure panels.

Another object of the present invention is to provide a method and apparatus which will fold and heat seal closure flaps over the top of a previously closed carton having closure elements sealed with thermoplastic adhesive without softening the previously sealed adhesive or in any way injuring the previous seal. y

Other objects and advantages will become ap'- parent in the following specification, taken in connection with the accompanying drawings, in which Figure 1 is a perspective view of a carton of the general type which is closed by the method and mechanism of the present invention;

Fig. 2 is a perspective view illustrating the carton in the machine, after the opposed closure elements are overlapped and sealed, and the adjoining closure elements pressed into triangularly shaped ears by the operation of other closing machinery;

Fig. 3 is a perspective view of a section of the carton carrying turret, showing the protective supporting and insulating plate positioned over the carton top;

Fig. 4 is a detailed sectional view illustrating the operating mechanism for the protective plate, the section being taken along line A-i of Fig. 3;

Fig. 5 is an enlarged fragmentary sectional view taken along line 5-5 of Fig. 3 illustrating the position of the carton flap;

Fig. 6 is an enlarged fragmentary view taken in front elevation, showing the action of uplifting the carton ears;

Fig. 7 is a view of the mechanism of Fig. 8 showing the iiap being folded over the carton;

Fig. 8 is a perspective view of the flap folding mechanism having a portion of the mechanism broken away to illustrate the linkage for rotating the folding shoe;

Fig. 9 is a front elevation of the ear folding mechanism showing the path of movement of the folding shoes and having a portion of the mechanism removed for clarity;

Fig. '10 is a perspective View taken from outside the turret illustrating the carton flap folding station for folding the flaps inwardly over the carton top;

Fig. 11 is a. perspective view of the mechanism of the folding station for folding the carton ears, taken from inside the turret;

Fig. 12 is a perspective view of the mechanism of the station for applying heat to the folded carton ears;

Fig. 13 is a fragmentary sectional view taken along line |3-l3 of Fig. 12, showing the relative positions of the carton closure elements;

Fig. 14 is an enlarged fragmentary sectional view taken along line lll-I4 of Fig. 12, illustrating the relative positions of the closure elements;

Fig. 15 is a perspective view showing the conguration of the heating head;

Fig. 16 is a perspective view of the carton at the heating station, having the operating mechanism removed to illustrate the position of the carton ears;

Fig. 1'7 is a perspective view of the mechanism for holding down the carton ears and folding the cover ap over the ears; and

Fig. 18 is also a perspective view of the mechanism for holding down the carton ears and for folding the cover nap.

The mechanism illustrating the preferred embodiment of the present invention is used to perform closing operations on a carton, a portion of the total closing operation having been completed by previous mechanism. Such mechanism is preferably of the type shown in the co-pending application entitled Carton Closing Machine, Fischer, Hedin, Swanson, and Wissman, Serial No. 206,464, filed December 23, 1950. A carton of the type folded by the machine shown in this co-pending application is illustrated in Fig. l. It is to be understood that other similar types of cartons may be handled by the present invention. The machine is, however, best adapted to complete the closure of a carton of the type illustrated.

Referring now to Fig. 1, the carton is formed of layers of material forming an inner liner layer 2B and an outer covering layer 2l. The side walls extend `above the carton top to form top closure panels. rI'he outer covering layer has received vertical slits along the edges of the front closure panel to form a single top, cover flap 23. In previous folding operations, the liner closure panel 24, which lies adjacent the cover iiap has been folded inwardly over the top of the carton. The inner and outer closure panels on the sides of the carton have been creased outwardly and doubled upon themselves to form multiple layer triangularly shaped naps or ears 25. .The rear inner and outer closure panels 26 were folded over the top of the carton to overlap the inner front closure panel in the manner shown` in Fig. 1. The overlapping panelsV and triangular ears were rmly pressed together and received an application of heat to soften the thermoplastic adhesive which coats the closure panels between the layers of material. The thermoplastic was then cooled to form an impervious seal between the overlapping front and rear closure panels and to laminate the laterally extending ears. The above described operations are performed by suitable machinery, such as that shown in the above-mentioned co-pending application, before the carton is received by the mechanism shown in the present application. The carton sealed inthe above described manner is shown in Figs. 2 and 3. The mechanism shown is adapted to closing the top. of the carton, but the invention could ,be further utilized for closing either of the carton ends. y Y.

The pre-sealed carton is shown carried in a pocket 2'? on a turret Ztfwhich is intermittently rotatable about a central post 2.8. as shown in Fig. 4. Curved rails 32 and 3l hold the cartons in the pockets, being supported on vertical posts 49. The turret is of the type shown in the copending patent application entitled Carton Closing Machine, Serial No. 206,464, filed December 23, 1950, Fischer et al., and a complete illustration of this type turret may be found in that application.

The embodiment of the present invention shows the folding devices adapted to function 0n a carton carried on a rotating turret, the carton remaining in the same turret in which the previous folding operations were performed. The invention may, however, easily be adapted to operate on a carton carried by other types of mechanism in which the carton is placed after receiving the first folding and sealing operations.

The method of our invention encompasses folding flaps of a carton over pre-sealed closure elements in such a manner as to obtain a final closure which is characterized by the absence of stresses and strains in the laminated material forming the closure. To accomplish this, the thermoplastic adhesive forming the laminations of material in the flaps is softened to permit the layers of material to shift with respect to each other. The softening heat is added only to the iiaps, however, so as to not disturb the previously sealed closure elements. The flaps are then maintained in folded position while the thermoplastic adhesive hardens. The addition or softening or annealing heat relieves all stresses in the carton flaps and obtains a stable well-sealed carton.

Referring to the drawings and the mechanism embodying the preferred form of our invention, a protective supporting heat insulating blade is shown in detail in Figs. 2 and 3. The blade 32 is formed of a thin flat metal plate of rectangular dimensions substantially equal to the top of the carton. The blade is slidable over the top of a carton to mechanically protect the underlying sealed closure elements from damage and functions to thermally insulate the sealed closure elements.

The blade is suitably secured to a carrying plate 33 which has bars 34 fixed to the lower surface. Trunnions 35 on the outer ends of the bars support rollers 36 which roll in guide slots 31 on members on the turret to afford movement of the plate in a radial direction. A bracket 38 is secured to the rea-r edge of the plate, and a pin 39 extends across the bifurcated end thereof. This pin is cradled in the bifurcated end of a pivotal arm 40 (Fig. 4) which is rocked tc slide the protective plate over the top of the carton. To this end a pivotal lever 11| has a cam follower 2 on its upper end which rides in the track of a cam @3 which is stationary as the turret rotates, being mounted on the post 29. A connector link 4d connects between the stub lever lil and the pivotal arm 4i! to transmit motion therebetween.

The turret is rotated by steps to carry the cartons to closing stations. When the mechanism at the station has performed its particular function, the turret is indexed to a succeeding station.

As the turret is indexed up to the ap folding station, illustrated in Figs. l0 and l1, the cam 43 causes the protective plate to be slid out over the top of the carton from the position shown in Fig. 2 to that shown in Figs. 3 and 4. It will be noted that the rear carton topclosure panel 2t overlies the front closure panel 2d and therefore the blade moving outwardly slides over the sea-m in the direction in which it is formed without danger of catching the overlapped edges. The plate, sliding over the carton, presses downwardly upon the top of the carton tending to hold the seam together.

A curved rail 41 supported on a vertical post 49 rides over the top of the cover flap 23 to hold it out of the way for folding operations (see .Fig.16

When the carton reaches the flap folding station, the ears 25 are folded upwardly, being piv oted about their line of attachment to the care ton through 180 to overlie protective plate 32. This action is illustrated by Figs. 5, 6 and 7. The side edges of the plate are substantially coincident with the line of attachment of the flaps to the carton and will form a straight even carton edge as the flaps are creased over the edge of the blade. The flaps extend laterally to lie on the upper nat surface of spring leaves 45 which are positioned adjacent the carton carrying pocket on the turret. Raising the leaves will crease the naps against the side edges of the plate.

The action which rst occurs at the flap or ear folding station is the pivotal movement of the kicker lingers which are caused to move up into the slots 48 on the turret to strike the spring leaves 45 which underlie the carton ears 25. The leaf` 45, moving from the position of Fig, to that of Fig. 6, pivots the ear out of the plane of the carbon top to a Vertical position creasing it against the side edge 5| of the plate. As the finger moves downwardly out of the slot, the

The spring leaves which lie under the carton ears and lift them to vertical position are fiat thin spring blades having resilience which holds them fiat on the surface of the turret. The spring leaves are suitably attached at one end 52 to the top of the turret. The kicker fingers 46, which strike the leaves, are carried on a pivotally mounted shaft which also carries an operating arm 58 (Figs. 8 and 10).

The folding' shoe 54 then moves underneath the carton ear, to force it up over the top of the carton, pressing it iiat upon the top of the protective hladc.- The lower face of the shoe exerts a downward pressure upon the ear to crease the ear over the edge 3| of the protective blade. The plate having substantial rigidity prevents any downward force from reaching the sealed overlapping closure panels and thereby prevents damage from being done to this seal.

Referring to Fig. l0, a tower 59 is suitably mounted on an annular framework 60 which surrounds the turret. The tower forms a support for the operating mechanism of the folding station. Journaled in the bottom of the tower is a constantly rotated short shaft 62 which, through bevel gears li, rotates the cam shaft 6G carrying a plate cam Se. The shaft t2 may be'rotated by power means, not shown, through bevel gears S1, or may be part of the drive system illustrated in the abovementioned co-pending application. A pivotal arm ld, carrying a cam follower 12, is pivotally carried on a irunnion 14 secured tothe tower. A push rod 'i6 connects the end of the pivotal arm l0 to the arm 58. A tension spring 18 connected between the rocker arm and the tower pivots the rocker arm to cause the fingers 6. lower drops to a low point on the cam. The fingers have a positive return by the action of the cam.

The operation of the folding shoes, which fold the flap over the carton, is accomplished through the following mechanism. Mounted on the end of the cam shaft f, a sprocket 80, by means of a. chain B2, rotates a shaft 84 also carrying a sprocket 86. A pivotal arm 88 carrying a chain tightening sprocket 90 is mounted on a boss 92 on the tower and secured in the desired position by means of a stud 94 threaded into the boss. The upper shaft 84, being rotatably mounted in the tower, also carries a pinion gear 96 which rotates a gear 98 mounted on a crank shaft |00 and also rotates a gear |62 which rotates gears |04 and |06 mounted on crank shafts |08 and |0.

On the inner ends of the upper crank shafts |00 and |08, as shown in Fig. l1, are mounted cranks ||2 and H4, respectively, which are connected to a pair of folding shoe holders ||6 and ||8. At right angles to the holders and at their lower ends are mounted the folding shoes |20 and 54 for folding the ears over the top of the carton onto the protective plate. The shoe 54 is slightly longer to fold one ap ahead of the other. This is of advantage where longer flaps are present and there is danger of interference between the flaps as they are folded. The lower cranks |2| and |22, mounted on shafts 84 and ||0, each rotatably carry a sliding block |23 which is mounted to slide in an elongated vertical slot |24 in the shoe holders. The connection between the cranks and the holders may be observed in detail in Figs. 8 and ll. It will be noted that the lower crank position is advanced several degrees over the position of the upper crank and that the lower crank is somewhat longer to obtain the unique motion given the folding shoe. The path of motion is indicated in Fig. 9 by the dotted arrows |26.

In operation, the crank shafts are caused to rotate continuously and the folding' shoes are given rotation through their path of movement. It will be seen from the drawing (Fig, 7) that the toe of the shoe catches beneath the carton ear and forces it over the top of the carton, the base of the shoe creasing the ear over the edge of the protecting plate and forcing the ear downwardly upon the top of the plate. The movement being continuous is of suihcient velocity to achieve the folding of the ears during the period of time the carton resides at this station but is not fast enough to cause wrinkling or deformation of the ears. The shoe, having accomplished its folding, moves back and upwardly in almost a straight line path to a. position where it will not interfere with a succeeding carton being moved into the folding station.

The ears of the carton, being formed of layers of carton material, have been placed under stress by virtue of their being bent around the sharp edge of the protective plate. The inner layer |28 of the .carton flap of the carton, being bent around a sharper radius than the outer layer |30 of the flap, is under a compressive stress, whereas the outer layer is under a tensile stress (see Figs. '7 and 14, Fig. 14 showing the laminations of the flaps in detail); The layers are fixed together by the laminating vadhesive and cannot slide to relieve the stress. To relieve this condition and permit the layers of material to slide with respect to each other, heat is applied to the ears to soften the thermoplastic adhesive between the layers.

46 to kick into the turret slot 48 Awhen thefol.- .75 While the adhesive is in a softened condition, the

stressed layers will be permitted to shift and assume a normal unstressed condition. This application of heat performs, in eect, an annealing process, relieving stress and resulting in a stronger closure when the thermoplastic is again hardened.

The mechanism for applying the annealing heat is shown in Figs. 12 through 16. A tower |32 is suitably mounted on the annular framework 60 and carries in its base a short shaft |34 which is connected to rotate with segment shaft 62 by means of bevel gear |38 which meshes with bevel gear E1 carried on shaft E2. The short shaft |34 carries a plate cam |33. A rocker arm pivotally mounted in the tower base carries a cam follower |42 at one end and is connected to a similar rocker arm |44 mounted at the upper end of the tower by means of the push rod H16 which is adjustable in length. A spring |45 connects between the lower rocker arm |40 and a bracket |41 on the tower to hold the follower |42 in contact with the cam |38 and pivot the arm as the cam is rotated. The heating mechanism Vis carried on a cross head |28 adapted to slide on vertical guide bars |50. A pin |52 is carried across a deep channel |54 in the cross head and extends through an elongated slot |58 in the upper rocker arm. Pivotal movement of the rocker arm will cause vertical reciprocation of the cross head.

At the lower end of the cross head is carried a heater block |53. Electrical leads connect between the heater and the connector box E52 on the cross head and leads |64 connect to a suitable source of electric current. the heater is contoured to match the shape of the ears, that is, the face of the heater block has a relieved portion |68 which overlies the space between the ears (see Figs. l5 and 16).

As the heater block is lowered upon the top of the carton ears 2?, the face |66 of the block contacts and transmits heat only to the earsV of the carton.

The cam and operating linkage are so arranged that the high portion of the cam positively raises the heater. The positive action of the cam insures that the heater will not be left contacting the carton when the turret indexes in the event the mechanism should stick.

The position of the protective plate 32 with respect to the carton closure elements is shown inA Figs. 13 and 14. lt will be readily seen that, were it not for the protective plate lying beneath the carton ears, heat applied to the ears would be transmitted to the underlying overlapped and sealed closure elements. This heat would undoubtedly soften the thermoplastic, forming the seal, and would at least weaken the closure. if not damage it completely. Further, since the heater block must be brought down upon the A ears with pressure to obtain adequate heat trans mission to the ears, if it were not for the strength of the protective plate, the pressure would dam age the seal formed by the overlapped closure elements.

The plate being cool absorbs the heat which.

penetrates the ears, and does not rise to the temperature at which the thermoplastic would become softened, and therefore the sealed layers below are not heated to adhesive softening tem- The lower face |66 of Lll) `ported by the vertical post 49.

flaps.

The thermoplastic between the laminations which form the ears is now softened and permits the stressed layers of material to shift to an unstressed position. The adhesive which was crumbled due to folding the ears melts and rehardens to a solid structure. While the flaps are in the folded position, the thermoplastic material is permitted to cool and solidify, forming a rigid seal.

It is to be observed that in the operation taught by the present invention a tight seal of thermoplastic adhesive may be formed and then additional closing elements folded over the top of the seal to protect it. These additional elements may be again heated for purposes of relieving stress or for forming a second seal without in any way .damaging the original seal. lt may be seen that flaps overlapping each other could be joined by heat over the rst seal without danger of causing leakage by damage to the seal. In a broader aspect, the present invention permits nrst sealing the carton and permits any manner of subsequent operations which require heat on the top of the fragile sealed carton without damaging the seal.

The mechanism at this Iheating station is provided with a no-carton no-operation device. A vertical shaft |14 is rotatably carried in the tower on brackets |15 and |12 and carries at its lower end an arm having a roller |82 for rolling against the peripheral surface of the turret. If no carton is present in the turret pocket, a spring |03 pivots the arm into the empty pocket to rotate a stop finger |84 carried on the top of the shaft |14 beneath a bracket |80 which is secured to the pivotal arm |44. This prevents pivotal movement of the rocker arm |44. A stop |88 mounted on bracket |18 limits the pivotal movement of the arm |80. This mechanism serves to prevent the heated head from being lowered directly on the protector plate when no carton is present in the turret pocket, which would overheat the plate.

As the turret is indexed from the heating station, the folded heated flaps 25 are cammed under a curved stationary rail |90 (Figs. 17 and 18). The flaps are thus .held down to the top of the carton while the softened adhesive hardens. This rail is heated by a block itil containing heating element supplied by electricity through leads |94. The block and rail are supported by an arm clamped in a holder |02 which is sup- The block is secured to the rail to warm it to a degree to prevent Wax from collecting and to promote smooth slid- .ing of the carton.

As the carton moves, the cover flap 23 begins camming gradually on the inwardly curved folding-rail 202 until it is folded completely over the The forward edge 20S of the protective platev lies along the line of attachment of the Fcover ap and the .flap is creased smoothly over this edge to form a sharp carton edge.

As the carton reaches the position opposite platform 204, as shown in Fig. 18, the ejecting plate or inner wall 205 of the turret pocket is moved outwardly, ejecting the carton from the turret pocket and sliding it over the platform 204. As the carton is ejected from the turret pocket, the protective plate 32 is withdrawn to a retracted position where it remains, cooling, until it is again slid over the top of a succeeding carton for a repetition of the folding operations performed on the present carton.

The mechanism for operating the ejecting -carrying rod 268 on which the ejecting plate 266 is mounted. The rod is supported in a bearing surface 256 in the turret and connected to an operating lever 2|2 pivotally mounted on a bracket 2 it on the turret. A follower 2 i 6 on the lower end of the lever is engaged by a cam 256 on a shaft 220 rotated by means not shown. The cam rocks the lever to force the ejecting plate outwardly to eject the carbon, and a tension spring 222 between the lever and turret body returns the plate.

As the carton is ejected, the folded ap is pressed beneath an adjustable blade 224i and a pressure plate 226. Both are carried on a framepiece 228, the blade being vertically adjustable by virtue of a thumb screw 230 threaded in a block 232 on the rear of the plate. The plate 226 is supported by pins 234 loosely mounted in the support 228. Springs 236 urge the pressure plate downwardly on the top of the carton to hold the flaps against the carton top while the adhesive cools. Portions of the machine illustrating the preferred embodiment of the present invention are shown in the co-pending application entitled Mechanism for Folding Carton Flaps, Serial No. 206,463, filed December 23, 1950.

To complete the closure of the carton, the cover nap 26 must be heated and sealed to the carton top. This operation may be accomplished by other suitable packaging machinery, preferably of the type shown in the co-pending application entitled Method and Apparatus for Sealing Cartons, Serial No. 206,461, filed December 23, 1950, Fischer.

The present invention has provided a method and mechanism for folding laminated iiaps over a carton top and for relieving the folding stress in the cartons by application of heat. This has been accomplished without danger of causing injury to the pre-sealed underlying heat sealed closure naps. The method and mechanism is well adapted to usage with a carton which is relatively fragile in strength as the provision of the unique protector plate prevents all mechanical forces from reaching the pre-sealed closure and allows a substantial amount of pressure to be used in folding the iiaps over the carton.

While the invention is susceptible of various modifications and alternative constructions, we have shown in the drawings and have described in detail the preferred embodiment. However, it is to be understood that we do not thereby intend to limit the invention to the specific form disclosed, but intend to cover all modincations and alternative constructions falling within the spirit and scope of the invention as expressed in the app-ended claims.

We claim as our invention:

l. A mechanism for folding carton closure iiaps over the end of a carton sealed with thermoplastic adhesive comprising a protective insulating plate movable over the sealed carton end to protect the seal from pressure and heat, means to fold the carton closure flaps over the end of the carton against the plate, and means to apply heat to the folded flaps while the plate is beneath the iiaps.

2. A mechanism for folding carton closure flaps laminated with thermoplastic over the top of a sealed carton comprising a fiat thin protective plate having dimensions substantially equivalent to the end of the carton, means to position the plate on the sealed carton end, folding means for folding the carton flaps about 1'0 the edge of the plate onto the plate, and means to apply heat to the folded carton flaps.

3. A mechanism for folding carton closure ears laminated with thermoplastic extending from the side of the carton over sealed carton closure elements and a flap extending from the front of the carton, comprising a flat thin insulating and supporting plate having a forward edge lying substantially coincident with the line of attachment of the flap to the carton, means to fold said ears over the top of the carton against the plate, means to apply heat to the folded ears, and means to fold the flap over the carton top to overlie the ears.

4. A mechanism for sealing the top of a carton having opposing closure panels laminated with thermoplastic folded in the overlapping and sealed relationship and side ears formed of laminations of the adjoining closure panels, comprising a thin protective insulating and supporting plate, means to slide the plate over the sealed carton in the direction which the overlying closure panel overlaps, means for folding the side ears over the top of the plate, and means for api plying heat to the folded ears.

5. A mechanism for folding the side ears laminated with thermoplastic and front iiap of a carton comprising a rectangular flat protective plate, means to move the plate over the carton top with the front edge of the plate substantially coincident with the line of attachment of the flap to the side wall and the side edges of the plate substantially coincident with the line of attachment of the ears to the carton, means to fold the side ears over the top of the plate, means to apply .a limited amount of heat to the folded ears, means to fold the flap over the ears, and means to withdraw the plate from beneath the ears and flap.

6. A mechanism for folding the ears of a carton over closure elements sealed with thermoplastic adhesive comprising folding members folding the ears over the carton top, means for applying heat to the folded ears, and means positioned between the ears and sealed closure elements to thermally separate said ears and closure elements to prevent the heat applied to the ears from softening the seal between said closure elements.

'7. The method of folding the ears of a carton having front and rear top closure panels sealed and overlying the top of the carton and two top closure panels joined thereto folded and laminated with thermoplastic adhesive to form double thickness triangular laterally extending ears, the method comprising folding the ears inwardly over the top of the carton, and applying heat to the ears softening the laminating thermoplastic to relieve the stress at the line of attachment of the ears to the front and rear panels by permitting relative shifting between the thicknesses forming the ears.

8. The method of folding ears of a carton having a first closure panel folded over the top of the carton and .a second opposing panel folded over and sealed by thermoplastic adhesive to the first panel and having double thickness ears attached to the closure panels and side walls and laminated by thermoplastic adhesive, the method comprising folding the ears over the top of the carton, heat insulating the ears from the iirst and second closure panels and applying heat to the folded ears softening the thermoplastic adhesive which forms the laminations to relieve the stress due to bending the laminated ears and permit the adhesive to reset with the ears in folded position.

9. The method of folding the ears of a carton having a first closure panel folded over the top of the carton and a second opposing panel folded over and sealed by thermoplastic adhesive to the rst panel and having double thickness ears attached to the closure panels and side Walls and laminated by thermoplastic adhesive, the method comprising folding the ears over the top of the .i

carton, heat insulating the ears from the first and second closure panels, mechanically supporting the ears in .an upward direction to prevent pressure on the sealed panels, and applying heat and 12 pressure to the ears to soften the thermoplastic and relieve the folding stress in the adhesive and carton material and to press the laminations together in unstressed relationship.

References Cited in the file of this patent UNITED STATES PATENTS Number Name Date 1,341,408 Armstrong May 25, 1920 2,018,806 Richard Oct. 29, 1935 2,196,666 Moore Apr. `9, 1940 2,412,546 Waters Dec. 10, 1946 2,524,032 Back Oct. 3, 1950 

